During his 15-year tenure, Curt Nonomaque helped Vizient grow into the nation's largest group purchasing organization, serving more than 3,100 health systems. Byron Jobe, the GPO's chief administrative and financial officer, will take over in March.

Optima Health CEO Michael Dudley will retire at the end of the year. His successor, Dennis Matheis, comes from Anthem, where he ran the national insurer's exchange business and worked on integration for the proposed Anthem-Cigna merger.

Dr. Mitchell Katz, a Brooklyn native who currently heads up the Los Angeles County Health Agency, faces daunting financial challenges if he's confirmed to lead New York's 11-hospital municipal health system.

Singleton oversaw the growth of the Falls Church, Va.-based system from $500 million to $3.3 billion in revenue. Recently, he was involved in efforts to bolster Inova's position as a national leader in precision medicine and cancer research.

Dr. Mark Schuster, a well-respected pediatrician and researcher at Boston Children's Hospital, was appointed the founding dean and CEO of the Kaiser Permanente School of Medicine, which is slated to open in 2019.